The present invention relates to a seat track slide device for a vehicle and, specifically, a lock mechanism for selectively restricting and permitting movement of an upper rail relative to a lower rail.
A conventional lock mechanism for a seat track slide device is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2005-225386. The lock mechanism includes a pair of lower rails, a pair of upper rails, and a pair of lock levers. The lower rails are fixed to the floor and the upper rails are slidable on the corresponding lower rails. Each of the lock levers is accommodated in the corresponding one of the upper rails. Each lock lever is pivotally supported by a support shaft in the corresponding upper rail. The lock levers are connected to each other through a handle. Each end of the handle is inserted into the corresponding upper rail from the front end of the upper rail and connected to the front end of the associated lock lever in the upper rail by means of an interlock support portion. Being interlocked by manipulation of the handle, the lock lever is selectively engaged with and disengaged from a lock hole of the corresponding lower rail.
Typically, movement allowance is ensured for each of the interlock support portions, which are arranged between the corresponding ends of the handle and the front ends of the associated lock lever. This allows the handle to pivot relative to each lock lever by an amount corresponding to the movement allowance with the lock levers maintaining their locking states, when the seat track slide device receives force inadvertently due to, for example, a car collision.
In the conventional lock mechanism, each end of the handle, which is inserted into the corresponding upper rail from the front end of the upper rail, is connected to the front end of the associated lock lever in the upper rail through the interlock support portion. This easily causes contact between the handle and the upper rails when the handle pivots relative to the lock levers, thus limiting the range in each upper rail that allows the handle and the associated lock lever to pivot relative to each other. As a result, the lock levers are prevented from sufficiently exerting their unlocking prevention functions.